Re: night force scopes ?
Have a bit of time on these scopes. Don't forget the MK4's have smaller objectives so some of this is apples to oranges - 40mm vs 50 & 56mm. Also MK4's are fixed power and NXS are all variables.
Here are a few points:
Optics - image sharpness, brightness, sharp to edge of field, color correction
- I would say the NXS, no doubts
Turrets - NXS has great tactile feel, sharp clicks easy to work, easy to zero.
MK4's are spongy when new, difficult to feel clicks, not snappy. Improve with use but still not "snappy" clicks like the NXS or Nikon 6.5-20. Need to take a half-hour and just twist the hell out of them to work them in, greatly improves the feel of the clicks.
Both turrets are very rugged, well sealed, NXS seems easier to crank. Both turrets are superbly accurate - return to zero, accuracy of adjustments.
MK4 available with very fine dot, duplex or Mil-dot reticles, NXS has more choices, NP-R2 is a great fine-reticle choice. NXS has best illumination system on the market, MK4 does not have illuminated reticle to date. Does have the M3 cam option, not available from NXS so far.
NXS has an optional fairly long screw-in plastic tube to cut barrel heat effects, not sure about MK4, not a catalog item, I bought a chunk of plastic tube to make one.
16X MK4 has a lot of elevation as you mentioned, more than the ten and the NXS.
Dream scope - a 3.5-15 40-44mm MK4 or NXS with smaller, fast turrets (complete range of zeros with only one revolution of the elevation turret).